Question

If the rays from sun converge at distance 12cm in front of a concave mirror. 1 poir
Where should an object be placed so that the size of its image is equal to
that of the object? *
12cm in front of the mirror
between 12cm and 6 cm in front of the mirror
24cm in front of the mirror
6cm in front of the mirror​

Answer 1

Explanation:

Since sun is an object at infinity, its image will fall athe focus.

So the focal length can be taken as - 12 cm.

Let us consider the object distance as x from pole.

Since image and object distance is same, take it also as x.

According to the equation,

1/v + 1/u =1/f

1/x+1/x=1/f

2/x =1/f

So, x=f/2

Therefore, u= - 6 cm

So it should be placed 6cm infront of the concave mirror.